The kanji symbols for sister-in-law are 嫂 (sister-in-law from older brother) and 弟妻 (sister-in-law from younger brother).
We write it as 鯉[koi] in kanji in Japanese.
There is no Kanji for "madsam."
弟, younger brother
Valentine had conflicting ideas with her older brother, especially when they start writing and her older brother tries to control what she thinks and can write.
you can't
There are two words for older brother, and they are used in different contexts. When talking to someone else and you refer to your older brother, you use a humble form. You would say "ani" (hiragana: あに kanji: 兄). When talking to someone else and you want to refer to their older brother, you use a polite form. You would say "onii-san" (hiragana: おにいさん kanji: お兄さん). You also use this word when talking to your older brother. So if I had an older brother I would call him "onii-san" or "onii-chan".
Older brother would be 兄 /a ni/ and younger sister would be 妹 /i mou to/. The same kanji for 'ani' (older brother) would be used in the word お兄さん /o nii san/ which is a polite word for 'older brother' and is more commonly used, also when calling to someone it can mean 'mister, man, dude, etc'.
Earthquake in kanji is written as 地震.
龍 or 竜
'Ojiichan' written with kanji isお祖父ちゃん.
you don't its written in katagana